In closures adapted to be used for packaging pressurized contents such as carbonated beverages, it is common to utilize a closure that has a base wall, a peripheral skirt within internal threads wherein the threads are interrupted to form venting passages so that when the closure is unthreaded from a container, the pressure of the contents is dissipated through the venting passages. When the closure is made of plastic, the tolerances in manufacture may result in the closure tending to move radially relative to the container so that at least some of the venting passages may be obstructed thereby adversely affecting the venting of the contents.
Among the objectives of the present invention are to provide a plastic closure wherein the closure permits an improved radial positioning with respect to the container; wherein the construction for providing such an action is obtained at minimal expense; and wherein the construction does not adversely affect the application of the closure to a container by automatic machinery; and wherein the closure can be used with glass or plastic containers.
In accordance with the invention, a plastic venting closure comprising a base wall, a peripheral skirt having internal threads adapted to engage the threads of a container and wherein the threads are interrupted at circumferentially spaced points to define axial venting passages for dissipating pressure of the contents as the closure is unthreaded from a container. At least some of the passages have an integral rib thereon spaced from the threads and extending axially. The radial thickness of each rib is less than that of the threads and preferably is arcuate in a radial direction and arcuate in a axial direction and preferably has an axial length greater than a transverse width such that it may span and engage swivel threads at the same time. The closure can be used with a glass container having a continuous thread and a plastic container having a continuous thread or an interrupted thread. By having each rib arcuate in an axial direction it may engage a plurality of threads at different radial points on the rib thereby minimizing application and removal torque while centering the container relative to the closure.